#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
#define rep(i,l,r) for(int i = l; i <= r; i ++)
#define rrp(i,l,r) for(int i = l; i >= r; i --)
const int N = 505;
int n, a[N], b[N], x[N][N], y[N][N];
LL f[N][N];
signed main() {
  cin.tie(0)->ios::sync_with_stdio(0);
  cin >> n, ++ n;
  rep (i, 2, n) cin >> a[i] >> b[i];
  rep (l, 1, n) {
    x[l][l] = a[l], y[l][l] = b[l];
    rep (r, l + 1, n) {
      x[l][r] = min(x[l][r-1], a[r]);
      y[l][r] = min(y[l][r-1], b[r]);
    }
  }
  rrp (l, n, 1) rep(r, l + 1, n) {
    f[l][r] = 1e18;
    rep (i, l, r - 1) f[l][r] = min(f[l][r], f[l][i] + f[i+1][r] +
    x[l][i] + x[i+1][r] + y[l][i] + y[i+1][r] - 2 * (x[l][r] + y[l][r]));
  }
  cout << f[1][n];
  return 0;
}